The present invention is directed to a drop wire clamp for suspending and directing a cable and, more particularly, to an improved drop wire clamp for more efficiently and effectively suspending and directing a double stranded cable.
Various types of clamps are employed to support and direct cables extending between supports and structures, such as from a utility pole to a building. One common type of clamp is referred to as drop-wire clamps. Such clamps are typically used with cables having two strands, a signal carrying strand and a support strand (also referred to as a messenger wire). A drop-wire clamp allows a cable, such as coaxial cable, to be supported and attached to a building, pole, or other support wire in a manner that lessens compromise to the signal transmission capability of the cable. The drop-wire clamp also is advantageous because it supports the weight of the cable and maintains tension on the line while relieving stress on the attachment points, such as at the attachment juncture with a pole or building.
Drop-wire clamps tend to fall into two general categories: (1) a wire wrap type; and (2) a compression type. With the first category, a portion of the messenger strand is separated from the signal carrying strand and wrapped around the clamp to secure the cable to the clamp. With the second category, the cable is secured to the clamp through pressure. In either design, it is critical that the clamp does not degrade the signal quality by damaging either the signal carrying cable or its insulation.
More specifically, with the first category, the drop-wire clamp utilizes a trough that accepts the signal-carrying strand. The trough is generally wider than the cable so as to receive it with a loose fit and, thus, avoid signal effecting damage to the signal carrying strand. Due to the loose fit between the signal carrying strand and the trough, the messenger wire is employed to secure the signal carrying strand in the trough of the clamp. Typically, these clamps have notches on the sides so that the wire is wrapped transversely about the clamp and is maintained in place by the notches or slots. This wrap holds the signal carrying strand in the clamp. Examples of prior wire wrap-type clamps are disclosed in U.S. Pat. Nos. 5,209,439 and D342,664.
A shortcoming with the wire wrap-type clamps, including those disclosed in U.S. Pat. Nos. 5,209,439 and D342,664, is that the user must alternate between hands when wrapping the messenger were transversely around the trough and/or constantly remove the hand from the messenger wire to grab the messenger wire on the other side of the cable and clamp to complete the transverse wrap. More specifically, for example, one hand is used to hold the clamp, while the other hand is used wrap the messenger wire part way around the clamp. The user must then switch hands to complete the wrap, i.e., the other hand is used to grasp the clamp while the first hand is used to complete the wrap. This hand alternating procedure is duplicated for each wrap and, thus, can include anywhere from one to four wraps, depending on the desired number of wraps. Although the wire wrap-type clamps address the issue of damage to the signal-carrying wire because of the loose fit between the trough and the wire, it has been found to be cumbersome, time consuming and overall more complicated than desired.
Another known shortcoming with the wire wrap-type clamps is the inflexibility with the manner in which the messenger wire can be wrapped about the trough to secure the signal carrying wire. That is, the design and positioning of the notches and slots commonly dictate only one wrapping pattern for the messenger wire.
With the second category, the drop-wire clamp secures the cable using compression. Compression designs may or may not use a trough to accept the signal-carrying wire, but the distinguishing feature of these clamps is that the signal-carrying wire is typically held to the clamp through some type of compressive force or pressure on the wire. Examples of this type of design are disclosed in U.S. Pat. Nos.: 3,960,461; 4,461,059; and 4,592,117.
For example, U.S. Pat. No. 3,960,461 discloses a clamp with two concentric cones that sandwich the cable. More specifically, a cable sits in a grove along the exterior of an inner cone and an outer cone or sleeve is slid over the inner cone. Due to the cone shaped surfaces, the cable is sandwiched under compressive pressure. U.S. Pat. No. 4,461,059 discloses a clamp with a trough that accepts the cable; however, the cable is secured in the trough under pressure of several rib members or fins. U.S. Pat. No. 4,592,117 discloses a clamp body that receives a wedge piece that contains a channel for accepting the cable. With the cable sitting in the channel of the wedge piece, it is then slid into the clamp. The cable is secured therein through pressure between the clamp and wedge piece.
Although these compression-type designs may eliminate the complicated wrapping procedure, one known shortcoming is that they may cause damage to the cable through the pressurized contact used to secure the cable to the clamp. This result is also known to disturb the spacing between the core wire and shielding braid.
Thus, there is desired an improved drop-wire clamp that includes the benefits of the wire wrap-type design to minimize damage to the signal-carrying wire, but also allows the cable to be secured into the clamp without complicated messenger wire wrapping procedures.